I have had good results using this shield with a careful selection of buffs and equipment.
A ribbon won't overcome the status effects, but Haste will negate Slow, and Regen will negate Sap and Poison to a degree. I've equipped a character with the Ensanguined Shield, a Renewing Morion (for Regen), and a Maximillian (for overall stats) and a Battle Harness (for automatic counters). I've also set Gambits to constantly cast Decoy, Bubble and Haste (and several healing spells) on the character with the Ensanguined Shield, and unlocked the Martyr license for that character.
The Decoy / Ensanguined Shield / Battle Harness combo works great - this character is pretty much the only one ever targeted by enemies and dodges most attacks; and they counter if they are hit. Hermes Sandles could be equipped for the Haste, if you prefer to save a Gambit slot. (Casting Mirror on this character is a bad idea unless you plan to heal via Items.)
There is no way to fix this shield.